318ti DRIVETRAIN VIBRATION

Tried searching this problem but the different attempts to name the problem thwarted that--

My daughter's 97 E36 318ti hatchback has a vibration under acceleration that feels and sounds EXACTLY like my 2002 would when the flexdisc (guibo) was chunking away. This happens at 3500rpm in 2nd and 3000 in 3rd.

I crawled underneath to take a look but the flexdisc looks fine and I have no idea how to evaluate the harmonic balancer on the driveshaft.

You might consider doing both at the same time.
I think it requires the same amount of labor.
Someone will correct me if I'm wrong.

No; not exactly. You can replace the guibo undoing only the two mounting bolts for the CSB. To replace the CSB, you usually have to drop the entire driveshaft, including the guibo. Since the guibo shows no obvious signs of failure, it's more likely the CSB.

Bottom line is, if you're doing the CSB, you may as well replace the guibo at the same time. OTOH, if you're replacing the guibo, you don't necessarily want to mess with the CSB.